In a statement outside court ahead of the hearing, Ms Steinfeld and Mr Keidan said: "Throughout our campaign we have met hundreds of couples like us who love each other and want a civil partnership so they can celebrate their commitment and strengthen the security of their family unit.

Image:The Court of Appeal ruled against the couple in February last year

"Their reasons for not wanting to marry vary from bad personal experiences to expense to conscience - but that doesn't matter.

"All they want is the choice of marriage or a civil partnership to suit them, which is currently available only to same-sex couples.

"We have a new Equalities Minister and she should take this opportunity to look afresh at the Government's position.

"It's time for the Government to stop making excuses which play with people's lives, and give choice to all now."

Campaigners say it is unfair that same-sex couples can enter into a civil partnership or get married, when mixed-sex couples can only get married.

They say this denies mixed-sex couples who do not want to get married the legal protections afforded to those in civil partnerships, such as the ability to inherit property tax-free from their partner.

They want the Government to extend the legal arrangement to heterosexual couples.